shared/numberUtils.ts

const num =
	'zero one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen'.split(
		' ',
	);
const tens = 'twenty thirty forty fifty sixty seventy eighty ninety'.split(' ');

/*
 * returns the written words for a given number.
 * Note: number must be uint (positive integar) and between 0 - 999,999
 */
export const number2words = (n: number): string => {
	if (n < 20) {
		return num[n];
	}
	const digit = n % 10;
	if (n < 100) {
		return tens[~~(n / 10) - 2] + (digit ? '-' + num[digit] : '');
	}
	if (n < 1000) {
		return (
			num[~~(n / 100)] +
			' hundred' +
			(n % 100 == 0 ? '' : ' and ' + number2words(n % 100))
		);
	}
	return (
		number2words(~~(n / 1000)) +
		' thousand' +
		(n % 1000 != 0 ? ' ' + number2words(n % 1000) : '')
	);
};